This application claims the priority of Korean Patent Application No. 2004-2683, filed on Jan. 14, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method for setting and applying preset white balance data of a digital photographing apparatus, and more particularly, to the application of such a method to an apparatus such as a digital camera or a digital camcorder.
2. Description of the Related Art
In general, a digital photographing apparatus, such as a digital camera or a digital camcorder, provides an auto white balance (AWB) function. According to the AWB function, when a digital photographing apparatus is shipped for the market, white balance data with respect to light sources is set in advance. When an image is photographed, the actual white balance data is compared with the white balance data which was set in advance. The apparatus then compensates for any differences with respect to the light sources by automatically adjusting the actual white balance data.
In a digital photographing apparatus, a preset white balance (PWB) function is provided with the auto white balance function. Through this preset white balance function, a user of the digital photographing apparatus can set a white balance arbitrarily. That is, in a state where a preset mode is selected in order to apply white balance data, white paper is placed in front of the digital photographing apparatus and the shutter button is pressed, or a part to be expressed in a white color is selected. Then, the digital photographing apparatus adjusts the brightness of red, green, and blue to make the color expressed in white color, and by doing so, a desired color can be expressed.
In the conventional digital photographing apparatus, for example, in the video camera apparatus of Japanese Application Laid-Open 1995-143496, preset white balance data is usually set for either a non-flash condition or a flash condition. Accordingly, if white balance data under a non-flash condition is set and flash light is emitted during actual photographing, it is impossible to apply accurate white balance data to the object being actually photographed because the flash light condition is different from the extracted preset non-flash condition.
Canon, Inc. attempts to solve this problem in some of its digital camera models, e.g., models S45 and S50. In these models, Canon uses a method in which, according to a current surrounding brightness level, it is determined whether or not the brightness level satisfies the condition for emitting flash light. If the brightness satisfies the condition, white balance data for a flash condition is extracted; however, if the brightness does not satisfy the condition for emitting flash light, white balance data for a non-flash condition is extracted.
In this case, if flash light is emitted under the flash condition and flash light is not emitted under the non-flash condition, application of accurate white balance data will be enabled. However, if the surrounding brightness level changes between the time that it is first sensed and the time when the actual photograph is taken, the white balance data of the actual photograph will not be accurate. For example, the images will be implemented with colors different from the ones determined by the preset white balance data if either the preset white balance data for a non-flash condition is first obtained considering the brightness and the surrounding condition changes such that flash light is emitted or if the preset white balance data for a flash condition is obtained but flash light is not emitted.